This invention relates generally to inflators for use in inflating inflatable restraint airbag cushions, such as used to provide impact protection to occupants of motor vehicles. More particularly, the invention relates to liquid-cooled inflators and the inclusion of performance enhancing additives therein.
It is well known to protect a vehicle occupant by means of safety restraint systems which self-actuate from an undeployed to a deployed state without the need for intervention by the operator, i.e., “passive restraint systems.” Such systems commonly contain or include an inflatable vehicle occupant restraint or element, such as in the form of a cushion or bag, commonly referred to as an “airbag cushion.” In practice, such airbag cushions are typically designed to inflate or expand with gas when the vehicle encounters a sudden deceleration, such as in the event of a collision. Such airbag cushions may desirably deploy into one or more locations within the vehicle between the occupant and certain parts of the vehicle interior, such as the doors, steering wheel, instrument panel or the like, to prevent or avoid the occupant from forcibly striking such parts of the vehicle interior. For example, typical or customary vehicular airbag cushion installation locations have included in the steering wheel, in the dashboard on the passenger side of a car, along the roof line of a vehicle such as above a vehicle door, and in the vehicle seat such as in the case of a seat-mounted airbag cushion. Other airbag cushions such as in the form of knee bolsters and overhead airbags also operate to protect other or particular various parts of the body from collision.
In addition to an airbag cushion, inflatable passive restraint system installations also typically include a gas generator, also commonly referred to as an “inflator.” Upon actuation, such an inflator device desirably serves to provide an inflation fluid, typically in the form of a gas, used to inflate an associated airbag cushion. Various types or forms of inflator devices have been disclosed in the art for use in inflating an inflatable restraint system airbag cushion.
One particularly common type or form of inflator device used in inflatable passive restraint systems is commonly referred to as a pyrotechnic inflator. In such inflator devices, gas used in the inflation of an associated inflatable element is derived from the combustion of a pyrotechnic gas generating material.
Pyrotechnic inflators also generally include a gas treatment element such as in the form of a filter. Such a filter form of gas treatment element may desirably serve to remove solids such as in the form of residual matter of the pyrotechnic gas generating material and such as may otherwise be entrained in the gas stream. Such a filter may also desirably serve to cool the gas formed by the combustion of a pyrotechnic gas generating material prior to the discharge of such gas from the inflator device. Filter elements, however, are often expensive and the inclusion thereof can add significantly to the cost and weight of an associated inflator device and inflatable restraint installation.
The automotive industry continues to demand inflatable restraint systems that are smaller, lighter, and less expensive to manufacture. As vehicles become smaller and more compact, corresponding changes to associated inflatable restraint systems are required in order to meet the constraints of these smaller vehicles.
An airbag inflator is a significant component of an inflatable restraint system. Accordingly, reducing the size, weight, and/or cost of an inflator can result in significant size, weight, and/or cost savings in the overall inflatable restraint system.
Thus, there is a need and demand for pyrotechnic-containing inflator devices and associated methods of operation such as to reduce or eliminate the need for the inclusion of filter elements. Further, there is a need and demand for such inflator devices and associated methods of operation that provide or result in improved or enhanced performance, such as in either or both increased gas output and gas output of reduced temperature.